Individuals with Insulin-Dependent Diabetes Mellitus (IDDM) face the life- threatening dilemma of attempting to avoid hyperglycemia without incurring hypoglycemia. This requires an accurate and convenient feedback loop of current blood glucose (BG). IDDM patients frequently use subjective BG estimates for such feedback. However, such estimates can be dangerously inaccurate. Blood Glucose Awareness Training (BGAT), which we developed and tested with healthy IDDM patients, has several immediate benefits: improved ability to accurately estimate BG, improved metabolic control, and reduced fear of hypoglycemia. The proposed project explores the mechanisms of these effects and evaluates methods to enhance BGAT immediate and long- term benefits. We will also assess the benefits of BGAT for patients who are at-risk for increased or undetected hypoglycemia including those: taking beta blockers, suffering visual impairments, and reporting hypoglycemia unawareness. The proposed project also investigates the effects of hypoglycemia on driving and other routine skills, as well as standard neuropsychological tests. One of the purposes of these studies is to identify reliable self- tests that indicate early hypoglycemia deficits. In addition, recovery of driving and other skills after hypoglycemia will be examined. To do this, 40 IDDM subjects will be administered different tests and driving simulations under various levels of hypoglycemia to determine effects on performance and evaluate subjects' awareness of these effects. Information from this and other studies will be used to develop an enhanced version of BGAT that will be administered to the at-risk patient groups described above (n=120). The effects of two versions of BGAT will be evaluated, as well as the effects of booster training. An 18-month post-BGAT followup will provide a test of both short- and long-term effects of BGAT on ability to estimate BG, metabolic control and hypoglycemia-induced automobile accidents and hospitalizations.